FA-1100 / Reliability / Member archive

Promote a standby after primary failure: Promotion succeeds while writes still route to the old primary · case 05

The failover promote operation is admitted even though promotion succeeds while writes still route to the old primary.

Member previewVariant 5 · 3 implementations · 9 checks per implementation

Case contract

Return a Boolean admission decision for promote a standby after primary failure. The record r must satisfy all of: r['primary_fenced'] is True; r['rpo_bound'][0]-r['rpo_bound'][1] <= r['rpo_bound'][2]; r['standby_writable'] is True; r['promotion_epoch'][0] > r['promotion_epoch'][1]; r['routing_switched'][0] == r['routing_switched'][1]. Extra tracing fields are ignored; validation does not mutate the record.

Why this case matters

A deterministic local contract for reliability. Each negative fixture violates exactly one invariant. No transport timing, persistence, cryptographic verification, or full protocol implementation is claimed.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
Promotion succeeds while writes still route to the old primary	`true`	`false`	Failed

MEMBER ARCHIVE

The complete case is available to members.

This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

Member access is invitation-based. Sign in with your invited account to inspect the sources.